Wheel loaders provide a travel mechanism that causes the vehicle to travel and a working machine that performs different kinds of work such as excavation etc. The travel mechanism and the working machine are driven by drive force from an engine. That is to say, drive force from the engine is distributed to the travel mechanism and the working machine. Thus output torque required for the engine differs in response to the conditions of usage of the travel mechanism and the working machine. Accordingly, there is a need to reduce fuel consumption in wheel loaders.
In the wheel loader disclosed in International publication WO2005/024208 a determination is made on whether the vehicle is performing excavation or traveling up a slope. Then, when the vehicle is performing excavation or traveling up a slope, the engine is controlled based on high output engine output torque line. When the vehicle is not either excavating or traveling up a slope the engine is controlled based on low output engine output torque line.
As in a working vehicle as described above, engine control is based on low output engine output torque line when the vehicle is neither excavating nor traveling up a slope, the quantity of fuel consumed is reduced thereby providing improved fuel economy. Further, when the vehicle is excavating or traveling up a slope the engine is controlled such that engine output torque line switches from low output torque line to high output torque line. This enables the high output torque necessary for excavating or traveling up a slope to be maintained, providing improved workability and travel ability.